In recent years, computers and television receivers have employed a variety of color display devices. A plasma display panel (hereinafter simply referred to as “PDP”), among others, has drawn attention as a color display device that allows the display panel to be large-size, thin, and light weight.
A PDP includes the following elements:                a front plate including a transparent substrate such as a glass substrate, on which display-electrodes, a dielectric layer, and protective film are laminated; and        a back plate including:                    a substrate, on which striped address electrodes are formed before a dielectric layer is formed,            barrier ribs, for forming a discharging space, disposed on the dielectric layer; and            a phosphor layer formed on lateral faces of the barrier ribs and on the dielectric layer, which phosphor layer is excited by ultraviolet rays to emit light in red, green, or blue.                        
The front and back plates are confronted each other and sealed, then neon (Ne) or xenon (Xe) is filled in the discharging space for discharging. Operating the foregoing PDP generates impurity gas because of the structure discussed above; thus, a degassing material is inserted into the PDP for absorbing and removing the impurity gas. In other words, the degassing treatment is provided. This instance is disclosed in Japanese Patent Application Non-Examined Publication No. 2000-311588. Further, providing the barrier ribs of the PDP with a degassing layer is proposed in Japanese Patent Application Non-Examined Publication No. 2002-531918.
However, the foregoing conventional degassing treatments are problematic. FIG. 8 shows a degassing structure in a conventional PDP. As shown in FIG. 8, back plate 52 is sealed by front plate 50 and sealing member 51. Back plate 52 is provided with exhausting hole 53, to which exhausting pipe 54 is coupled. Pipe 54 is filled with degassing material 55. The foregoing structure allows degassing material 55 to collect impurity gas in the discharging space through exhausting pipe 53. However, because the discharging space in the PDP is separated by barrier ribs 56, the impurity gas does not flow in the space, but diffuses for being collected by degassing material 55. Thus, only the impurity gas only around degassing material 55 is collected, and the impurity gas discharged to the image display area cannot be collected. In order to overcome this problem, exhausting pipes 53 are prepared at plural places on back plate 52, and degassing material 55 is also prepared at plural places. However, this case not only complicates the manufacturing process, but also weakens the strength of back plate 52.
FIG. 9 shows another degassing structure in a conventional PDP. As shown in FIG. 9, the PDP includes back plate 61 and front plate 60 including electrodes and a dielectric body, and a is equipped with degassing layer 64 on the top surface of barrier ribs 63. Degassing layer 64 forms parts of back plate 61, and each one of barrier ribs 63 has phosphor layers 62 on its side walls. Preparation of degassing layer 64 on the top surface of barrier ribs 63 can collect the impurity gas from overall the PDP more effectively. However, after forming barrier ribs 63, degassing layer 64 must be formed again and, thus, so that the manufacturing process becomes complicated. Further, the degassing material impairs the insulation property of barrier ribs 63, which affects the discharging characteristics.
On top of the foregoing problems, the conventional degassing material shown in FIGS. 8 and 9 needs to be heated at as high as approx. 400° C. to become activated.
The present invention aims to provide a method of manufacturing PDPs in which impurity gas can be collected from overall the PDP without an activation treatment at a high temperature.